Hey Guys, I would like to try converting a gas engine but with all the info here , I not sure which engine to look for.

I never flown anything over a .40 size plane, So I was thinking a 25/30 cc motor to start with??? any particular brand to look for.
I'll probally spad a plane to fit engine size, just looking for something easy to covert.

I asked around work and I've already got a few possiblities, A toro 4-stroke, a off brand small chainsaw, and maybe one old weedeater.

thanks in advance.